Abdominal exercise device



FIG. 1 is a perspective view of the abdominal exercise device showing our new design;

FIG. 2 is a side elevational view thereof, all side views being identical thereto;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for an abdominal exercise device, as shown and described. 